6 papers
The IACOB project XVIII. Prevalence of short-period binaries among Galactic helium rich O-type stars
C. Martínez-Sebastián, R. Gamen, O. G. Benvenuto +6
For decades, the origin of helium enrichment in O-type stars has remained an open question. In this study, we investigate the correlation between surface helium abundance and orbit…
The IACOB project: XVI. Surface helium abundances in Galactic O-type stars: indications for identifying binary interaction products
S. Simón-DÃaz, G. Holgado, C. MartÃnez-Sebastián +13
The presence of massive O-type stars with surfaces enriched by CNO-cycle products has been known since the early 1980s. For many years, internal rotational mixing was assumed to be…
The IACOB project: XVII. Nitrogen abundances in Galactic O-type stars: further hints for separating binary-interaction products from effectively single stars
C. MartÃnez-Sebastián, G. Holgado, S. Simón-DÃaz +2
Context. Growing evidence is revealing the crucial role of binarity in massive star evolution. This affects evolution models and demands a refinement of the available observational…
The lack of fast rotators in Cyg OB2. I. Insights from spectral reclassification of its B0 population
D. Galán-Diéguez, S. R. Berlanas, A. Herrero +4
Context. Cygnus OB2, in the Cygnus X complex -- one of the most active star-forming regions of the Galaxy -- hosts hundreds of O- and B-type stars at different evolutionary stages.…
An observational study of rotation and binarity of Galactic O-type runaway stars
M. Carretero-Castrillo, M. Ribó, J. M. Paredes +3
Gaia DR3 data have revealed new massive runaway stars, while spectroscopic surveys enable detailed characterization. The relative contributions of binary supernova (BSS) and dynami…
The IACOB project XIII. Helium enrichment in O-type stars as a tracer of past binary interaction
C. MartÃnez-Sebastián, S. Simón-DÃaz, H. Jin +4
There is increasing evidence that single-star evolutionary models are inadequate to reproduce all observational properties of massive stars. Binary interaction has emerged as a key…